Grand Campaign, 2p, playing central powers, Army-by-army mode, last patch.
Turn : Jan-Feb 1915, first redeployment phase.
As you can see in the screens below, the AI put one Russian detachement in France (in Avignon precisely) and a French colonial detachement in Russia.

That's not a thing that prevent my game to go on but it's something weird and I don't want to figh a whole Russian Army in the middle of France.

Of course there was a Russian Expeditionary Force that fought in France 1916-17 and French troops in Russia after the Revolution but...

Given my understanding of how redeployment is supposed to work in the game, such a redeployment should be impossible so obviously my understanding of WW1G is incomplete. Cannot offer any insights, sorry but if you have saved at the redeployment phase, perhaps Calvinus can figure out what's going on should you decide to post it here.

Hello, you are the 2nd customer who reported this strange issue. I've tried to reproduce it a lot of times, unsuccessfully. If you have a savegame just before AI performs this weird redeployment, do not hesitate to post it here (.SAV & .MAP, zipped), please!

Unfortunately my PC is k.o. so I'll not be able to work on this issue for many days, sorry.

I have a save i made just after i noticed the problem and i have a save long before (in the middle of my nov-dec 1914 movement phase)Maybe i cad reload the last one, funish the turn ans see if the problem is still here (and i'll made a save before)

You can lock the German colonial forces in Africa and Qintao by modding the WarPlanTurnRules.csv file, adding an immobilize turn rule for each of the German war plans. This prevents them from showing up in the swamps of East Prussia or wherever although this may still happen if they are rebuilt after being destroyed while in supply.

My Grand Campaign Naval Mod imposes this on the CP Player and AI alike until July 1916 (shameless plug I know, sorry).

Unfortunately there does not appear to be a method of getting the AI to differentiate between Askaris and Bavarians or any other ethnic group for deployment or rebuilding purposes.

I've encountered this strange phenomena too, at least a couple of times in different campaigns. But Alas, I have not kept a save that may reveal something. Sometimes (often) the AI places units in cut off provinces, so they immediately becomes isolated. But they never tries to break out, but slowly disintegrate. If I recall correctly, this odd thing appears quite early on in gameplay, but why I cannot say.